1. Field of the Invention
The present invention relates to a safety relief valve assembly for a fluid displacement apparatus and, more particularly, to a safety relief valve assembly for a refrigerant compressor used in an automotive air conditioning system.
2. Description of the Related Art
Many safety relief valves for refrigerant compressor applications are well known in the prior art. For example, Japanese Utility Publication No. H04-84976 discloses a safety relief valve device generally used in a refrigerant compressor for an automotive air conditioning system. The refrigerant compressor is provided with a safety relief valve device which automatically prevents excessive pressure build up in the compressor. The safety relief valve, which is mounted on the compressor housing, opens and closes in response to the pressure in the compressor if the pressure in the compressor or the cooling circuit abnormally increases.
When the safety relief valve operates, refrigerant gas including lubricating oil is emitted in the engine compartment of the vehicle. If the emission strikes a high temperature component of the engine, such as an exhaust manifold, smoke along with offensive odors and sometimes even fire result.
One attempt to resolve this problem was derived by the assignee of this application. Though not prior art, this attempt is indicative of the prior shortcomings of earlier solutions. Referring to FIGS. 1-3, relief valve assembly 10 includes valve mechanism 11 mounted on one end of a refrigerant compressor 100 and a cover member 18 attached to valve body 11a of valve mechanism 11. Valve mechanism 11 includes valve packing 15, valve member 14 surrounding valve packing 15, nut 13 disposed on the edge of valve body 11a, cap member 12 and spring 16 disposed between valve member 14 and cap member 12. Cap member 12 includes an opening 12a formed at the center radial axis thereof. Spring 16 biases valve member 14 and valve packing 15 toward the open end of passage 11b formed in the center of valve body 11a.
Cover member 18 comprises a hexagonal plate portion 18a, a connecting portion 18b perpendicularly extending from one end of hexagonal plate portion 18b, arm portion 18c extending from connecting portion 18b and a ring portion 18d extending from one end of arm portion 18c. Cover member 18 is secured to valve mechanism 11 such that arm portion 18c and ring portion 18d respectively hold nut 13 and valve body 11a, and hexagonal plate portion 18a faces opening 12a of cap member 12.
Cover member 18 is manufactured by blanking a plane plate and bending hexagonal plate portion 18a towards arm portion 18c at a 90.degree. angle as shown in FIG. 3. Cover member 18 is provided with connecting portion 18b which eases the bending of hexagonal plate portion 18a. Gap G (FIG. 1) is created between hexagonal plate portion 18a and arm portion 18c.
When the pressure in the cooling circuit and the compressor exceeds predetermined design pressures, the high pressure refrigerant gas causes valve member 14 and valve packing 15 to move away from the valve seat by overcoming the restoring force of coil spring 16. Refrigerant gas is then emitted in the direction of the longitudinal axis of valve body 11a through opening 12a of cap member 12. Thus, the refrigerant gas strikes and is directed along hexagonal plate portion 18a toward an area other than the high temperature components of the engine, for instance below compressor 100. When the pressure in the cooling circuit and the compressor decreases, valve member 14 and valve packing 15 return to the valve seat under the influence of the restoring force of coil spring 16.
Even in this configuration, however, it has been experienced that some of the refrigerant gas comes into contact with the high temperature components of the engine due to the presence of gap G. Thus, the problem has not been totally solved, and there remains the possibility of causing smoke or an offensive odor or even fire from the engine compartment of the vehicle.
These and other drawbacks are sought to be overcome by the invention of the referred embodiments.